Recent years have seen the development of stretchable and shrinkable films for use in packaging. The inherent film tension of these shrinkable films permits them to be wrapped around objects so as to compress (and "package") the objects without the film breaking. Known examples of such films include the trademark films PRESTO-STRETCH-GARD, PRESTO-BUNDLE-GARD, and PRESTO-STRETCH-GARD IV.
Various packaging techniques are known which use shrinkable films. One existing process and apparatus is the "Toroid" orbital stretch wrapper of the OVERWRAP Equipment Corporation of Fairfield, N.J. This orbital stretch wrapper utilizes a single roll of shrinkable film which is rotatably transported around an object to be wrapped. A conveyor belt mechanism moves the object to be wrapped through a wrapping zone defined by the rotational movement of the roll. The rotational axis formed by the drawing off of material from the single supply roll is situated parallel to the direction of movement of the objects.
Various problems associated with known packaging technology using shrinkable film include uneven or non-smooth wrapping of the film around the desired object, and uneven tension in the wrapping material as the object is packaged. The uneven tension (and associated uneven pressures) brought to bear on the objects may cause stackable objects to become displaced with respect to one another. Single objects which may not withstand the pressure necessary to tightly stretch the shrinkable film around the object can become deformed during packaging.
The U.S. patent to Lancaster, et al. (U.S. Pat. No. 4,317,322) teaches a rotatable circular device encompassing a conveyed object so as to cause wrapping materials to be spirally wound onto an object. This operation reduces the likelihood of non-smooth wrapping, but does not eliminate it due to the parallel placement of the roll of wrapping material with respect to the direction of the movement of the object. (Refer specifically to FIGS. 3 and 7 and Column 12 of the patent.)